904 tranny pan question

Ok guys I am having problems getting the factory 904 tranny pan to seal. I have tried cork gaskets, Felpro gaskets, using gasket material and using it dry and it will still puddle under the car after awhile. I can see drips on the front row of pan bolts. I am assuming that the pan isnt sealing. Can you tell me where I can get a cast aluminum pan for this at a reasonable price .